What is calcination? How does it differ from roasting?
Answer (1)
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Calcination: Heating the concentrated ore strongly in the absence or limited supply of air. This process is generally used for carbonate and hydroxide ores to decompose them into the metal oxide. Volatile impurities are also removed.
- Example: CaCO₃(s) → CaO(s) + CO₂(g)
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Roasting: Heating the concentrated ore in the presence of excess air. This process is mainly used for sulfide ores to convert them into metal oxides. Sulfur is removed as SO₂.
- Example: 2ZnS(s) + 3O₂(g) → 2ZnO(s) + 2SO₂(g)
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